Method for manufacturing container and apparatus for manufacturing container

ABSTRACT

A method of manufacturing a container made of metal, including a bottom portion and a body portion, being open on an upper face side, and having a shape in which the body portion expands outward toward the upper face side. The method includes a stretch forming step of expanding a diameter of a stepped cup body made of metal by operating a diameter expanding punch having a tapered pressing portion that is smaller in diameter than an inner diameter of the large-diameter cylindrical portion and larger in diameter than an inner diameter of the small-diameter cylindrical portion of the stepped cup body along a cylindrical axis direction from an opening side of the large-diameter cylindrical portion, in which the stretch forming step is performed at least once.

TECHNICAL FIELD

The disclosure relates to a method for manufacturing a container made ofmetal, open on an upper face side, and including a bottom portion and abody portion and to an apparatus for manufacturing a container.

BACKGROUND

In recent years, in order to conserve resources, reduce waste, and thelike, there has been a growing demand for a lightweight, inexpensive,and easily recyclable container that can be used as an alternative to acontainer made of paper, plastic, or the like.

It is conceivable to adapt a well-known container made of metal and openon an upper face side, which is used as tableware or as a container forfilling beverages, food, or the like (refer to JP 2003-128060 A, etc.).

As known containers open on an upper face side, containers made of metalthat are washed and used many times, such as those used for tableware,are well known. However, because of the need to increase durability inconsideration of long-term use, a certain plate thickness is necessaryto increase strength, resulting in higher material costs and moldingcosts and a heavier weight, thus making the container a highlyproblematic alternative to containers made of paper, plastic, or thelike.

In recent years, the recycling capabilities for metal can containershave improved, and using metal containers made of thin materials, suchas the one in JP 2003-128060 A, can now reduce material costs andmolding costs and has a lighter weight, while saving resources andreducing waste, even if used only once as tableware.

Nevertheless, there is a problem in that a container made of metal andhaving an open upper face side is not suitable in shape or structure forbeing stored and transported while empty and being used by a user whileopen.

Further, the growing global awareness of the need to preventenvironmental pollution, such as the ongoing pollution of the oceanscaused by plastics, has led to a demand for containers made of amaterial that can be easily recovered for recycling.

On the other hand, manufacturing a container made of metal and open onan upper face side requires a technique for forming a body portion intoa tapered shape as disclosed in JP 2006-224113 A and the like. However,the conventional method for manufacturing beverage cans is to form atapered shape only in a partial range in a height direction of the bodyportion, such as a neck and chime, and no method has been established toform a smooth tapered shape over a wide height range of approximatelyfrom 70% to 90% of the body portion of the container.

SUMMARY

An object of the disclosure is to solve the problems described above,and to provide a method for manufacturing a container and an apparatusfor manufacturing a container, by which it is possible to easilymanufacture a container having a body portion with a shape that expandsoutward toward an upper face side of the body portion.

A method for manufacturing a container according to an aspect of thedisclosure is a method for manufacturing a container made of metal,including a bottom portion and a body portion, being open on an upperface side, and having a shape in which the body portion expands outwardtoward the upper face side. The problem is solved by including a stretchforming step of expanding a diameter of a stepped cup body made of metaland having a small-diameter cylindrical portion having a bottomedcylindrical shape and a large-diameter cylindrical portion with anopening on an upper face side and contiguous to an upper end of thesmall-diameter cylindrical portion via a step portion by operating adiameter expanding punch having a tapered pressing portion that issmaller in diameter than an inner diameter of the large-diametercylindrical portion and larger in diameter than an inner diameter of thesmall-diameter cylindrical portion of the stepped cup body along acylindrical axis direction from an opening side of the large-diametercylindrical portion, and performing the stretch forming step at leastonce.

An apparatus for manufacturing a container according to an aspect of thedisclosure is an apparatus for manufacturing a container made of metal,including a bottom portion and a body portion, being open on an upperface side, and having a shape in which the body portion expands outwardtoward the upper face side. The apparatus includes at least one stretchforming die, each stretch forming die including a diameter expandingpunch having a tapered pressing portion that is configured to expand adiameter of a stepped cup body made of metal and having a small-diametercylindrical portion having a bottomed cylindrical shape and alarge-diameter cylindrical portion with an opening on an upper face sideand contiguous to an upper end of the small-diameter cylindrical portionvia a step portion by pressing along a cylindrical axis direction froman opening side of the large-diameter cylindrical portion and that issmaller in diameter than an inner diameter of the large-diametercylindrical portion and larger in diameter than an inner diameter of thesmall-diameter cylindrical portion of the stepped cup body.

According to the method for manufacturing a container according to oneaspect and the apparatus for manufacturing a container according toanother aspect, by performing the stretch forming step of expanding thediameter of the stepped cup body made of metal and having the bottomedcylindrical shape at least once, the diameter of the stepped cup bodycan be expanded without causing damage to the cup body, such as wrinklesor cracks. Thus, even when a wide height range of the body portion ofthe container is tapered, it is possible to easily manufacture acontainer with a desired smooth tapered body portion that expandsoutward toward the upper face side and is made of metal and easilyrecycled. In addition, since it is not necessary to operate the diameterexpanding punch with a long stroke, the manufacturing facility can bedownsized, and the manufacturing process can be sped up.

According to the method for manufacturing a container according toanother aspect and the apparatus for manufacturing a container accordingto another aspect, by repeating the stretch forming step a plurality oftimes, the body portion of the container can be reliably formed into thetapered shape over the wide height range. By repeating the stretchforming step from 2 to 10 times, the body portion of the container canbe more reliably formed into the tapered shape over the wide heightrange.

According to the method for manufacturing a container according toanother aspect and the apparatus for manufacturing a container accordingto another aspect, since an angle of the step portion of the stepped cupbody to a plane perpendicular to an axial direction of the stepped cupbody (horizontal plane) is from 0° to 60°, the stepped cup body can beeasily formed into the tapered shape over the wide height range whilesuppressing the occurrence of wrinkles or the like.

According to the method for manufacturing a container according toanother aspect and the apparatus for manufacturing a container accordingto another aspect, a diameter of a tapered pressing portion of adiameter expanding punch used in a stretch forming step performedearlier and a diameter of a tapered pressing portion of a diameterexpanding punch used in a stretch forming step performed subsequentlyare different from each other, so that the body portion of the containercan be reliably formed into a tapered shape over a wide height range.

According to the method for manufacturing a container according toanother aspect, by forming the body portion so that a line connecting anouter peripheral face at 10% height and an outer peripheral face at 90%height from a lowermost portion expands outward at an angle of from 2°to 15°, preferably from 3° to 10° (body taper angle) when a total heightof the container is 100%, the container can be manufactured with a shapethat has high strength, is easy to stack, and is easy for a user tohold, while suppressing toppling when the center of gravity is raised bycontaining beverages or the like. Containers formed with the body taperangle of more than 15° increase the distance between adjacent containerswhen arranged in upright postures, resulting in inefficient storage. Onthe other hand, containers formed with the body taper angle of less than2° are difficult to separate when stacked containers are separatedbecause the stacked containers stick to each other or the like.

Further, according to the container manufactured in this way, when thetwo containers are stacked, a projecting portion of the container placedabove projecting from the container placed below has a height of 20 mmor less from an upper end of the container placed below, so that theheight of a plurality of stacked containers can be reduced.

Furthermore, when transporting and transferring containers to a facilityfor filling beverages, food, or the like, a lid attachment facility, orthe like, the containers can be transported and transferred in a stackedstate, thereby improving efficiency in cans manufacturing, or the likeby filling beverages, food, or the like, and then sealing the filledcans.

According to the configuration described in another aspect, by makingthe thickness of the bottom portion 0.20 mm or greater, the center ofgravity can be lowered. Thus, the containers can be manufactured withgood self-standing stability.

Further, the thickness of the bottom portion is 0.35 mm or less, and thethickness of the body portion is from 0.10 to 0.22 mm in a height rangeof 50±10% when the total height of the container is 100%. This makes itpossible to reduce the material costs and the forming costs and lightenthe weight, and obtain a container that is formed into a shape in whicha line connecting an outer peripheral face at 10% height and an outerperipheral face at 90% height from the lowermost portion expands upwardand outward at an angle of from 3° to 10° when the total height of thecontainer is 100% (a more suitable shape).

According to the configuration described in another aspect, by setting aratio of the projecting portion to a height of the container to be from4% to 15%, the volume can be reduced while ensuring ease of separationby preventing the containers from sticking or the like when a pluralityof containers are stacked, thereby improving efficiency when storing andtransporting empty containers. The ratio of the above-describedprojecting portion to the height of the container is preferably 5% to9%.

According to the configuration described in another aspect, by makingthe body portion have a contact portion that prevents the body portionfrom coming into close contact with another container by reducing thecontact area with the other container, it is possible to obtaincontainers in which the body portions are reliably prevented from cominginto close contact with each other when a plurality of containers arestacked, and that are further improved in ease of separation because theportions other than the contact portion are non-contact and circulationof air between the containers can be ensured when individuallyseparating the stacked plurality of containers.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of a container manufactured by a method formanufacturing a container according to an embodiment of the disclosure.

FIG. 2A is a side view of a stepped cup body used in a method formanufacturing a container of the disclosure.

FIG. 2B is a side view of another stepped cup body used in the methodfor manufacturing a container of the disclosure.

FIG. 3A is a schematic diagram for describing a method for manufacturinga container according to the embodiment of the disclosure.

FIG. 3B is a schematic diagram for describing the method formanufacturing the container illustrated in FIG. 3A according to theembodiment.

FIG. 3C is a schematic diagram for describing the method formanufacturing the container illustrated in FIG. 3A according to theembodiment.

FIG. 4 is a side view of two containers, one being illustrated in FIG. 1, stacked on top of each other.

FIG. 5 is a partially enlarged cross-sectional view of the twocontainers stacked on top of each other illustrated in FIG. 4 .

FIG. 6A is a schematic diagram for describing a method for manufacturinga container according to another embodiment of the disclosure.

FIG. 6B is a schematic diagram for describing the method formanufacturing the container illustrated in FIG. 6A according to theother embodiment.

FIG. 6C is a schematic diagram for describing the method formanufacturing the container illustrated in FIG. 6A according to theother embodiment.

DESCRIPTION OF EMBODIMENTS

A container manufactured by a method for manufacturing a containeraccording to the disclosure will be described below.

As illustrated in FIG. 1 , the container manufactured by the method formanufacturing a container according to the disclosure is a container 100that includes a bottom portion 120 and a body portion 110, is made ofmetal, has an upper opening 101 open on an upper face side, and can bereplaced in shape with a well-known paper cup or plastic cup.

The body portion 110 of the container 100 has a tapered portion 111having an inverted truncated cone shape (tapered shape) that expandsoutward toward an upper side (upper opening 101 side), an upper sideportion 113 that is continuous between the tapered portion 111 and theupper opening 101, and a lower side portion 114 that is continuousbetween the tapered portion 111 and the bottom portion 120. The taperedportion 111 of the body portion 110 has, for example, a linear anduniform tapered shape in a cross-sectional view, and an angle θ thereofis 5°.

Further, the upper side portion 113 and the lower side portion 114 donot expand outward and have an approximately cylindrical shape.

The tapered portion 111 of the container 100 is formed with a uniformoutward expanding angle from 10% height to 90% height from a horizontalplane with a total height of the container being 100%, for example, whenthe container 100 is placed on the horizontal plane with the bottomportion 120 facing downward, so the outward expanding angle of a lineconnecting an outer peripheral face at the 10% height and an outerperipheral face at the 90% height from the lowermost portion (body taperangle), with a total height of the container being 100% is approximately5°, which is substantially the same as θ.

In the present embodiment, the bottom portion 120 is formed into asimilar shape to that of well-known two-piece beverage cans.

A fringe of the upper opening 101, that is, the upper end portion of thebody portion 110 is formed into a shape in which a sharp edge thereofdoes not come into direct contact with a mouth, for example, a curledshape, for use as a cup.

An embodiment (first embodiment) of the method for manufacturing acontainer according to the disclosure will be described below.

The container 100 includes a stepped cup body forming step of forming ametal sheet (blank) into a stepped shape having a bottom and twocylindrical portions with a large diameter and a small diameter toobtain a stepped cup body 200, and a stretch forming step of forming atapered portion 111 that expands outward toward an upper opening 101side by stretching the small-diameter cylindrical portion of theobtained stepped cup body 200 so that the diameter expands toward anopen end portion 201 side. After the stretch forming step, a curlforming step of curling an upper end portion of the body portion 110into a round shape is performed. Note that the curl forming step may beperformed before the stretch forming step or in the middle of aplurality of stretch forming steps.

The stepped cup body 200 has two cylindrical portions 260 and 280, onewith a small diameter and the other with a large diameter, connected bya step portion 270, as illustrated in FIG. 2A. The small-diametercylindrical portion 260 has a bottomed cylindrical shape, and thelarge-diameter cylindrical portion 280 is contiguous to an upper end ofthe small-diameter cylindrical portion 260 via the step portion 270 andis open on an upper face side.

An inner diameter of the small-diameter cylindrical portion 260 is equalto the minimum inner diameter of the tapered portion 111 of the bodyportion 110 of the container 100 desired. An inner diameter of thelarge-diameter cylindrical portion 280 is equal to the maximum innerdiameter of the tapered portion 111 of the body portion 110 of thecontainer 100 desired.

Heights of the small-diameter cylindrical portion 260 and thelarge-diameter cylindrical portion 280 in a direction of a cylindricalaxis X may be the same as or different from each other.

The step portion 270 is provided over the entire circumference of thestepped cup body 200 and has a step face 271 with an angle ofapproximately 0° to a horizontal plane perpendicular to the direction ofthe cylindrical axis X (i.e., parallel to the horizontal plane).

The stepped cup body may have, as a step face, an inclined face with anangle α of more than 0° and 60° or less to the horizontal planeperpendicular to the direction of the cylindrical axis X. Specifically,as illustrated in FIG. 2B, a stepped cup body 400 has three cylindricalportions 440, 460, and 480 of a small diameter, medium diameter, andlarge diameter, respectively, connected by two step portions 450 and 470spaced in a height direction. The smallest diameter cylindrical portion440 has a bottomed cylindrical shape, and the medium-diametercylindrical portion 460 is contiguous to an upper end of thesmall-diameter cylindrical portion 440 via the step portion 450, and thelarge-diameter cylindrical portion 480 is contiguous to an upper end ofthe medium-diameter cylindrical portion 460 via the step portion 470 andis open on an upper face side. Then, both step faces 451 and 471 of thetwo steps 450 and 470, respectively, are inclined faces inclined at anangle α radially inward and downward in the direction of the cylindricalaxis X. An inner diameter of the small-diameter cylindrical portion 440is equal to the minimum inner diameter of the tapered portion 111 of thebody portion 110 of the container 100 desired. An inner diameter of thelarge-diameter cylindrical portion 480 is equal to the maximum innerdiameter of the tapered portion 111 of the body portion 110 of thecontainer 100 desired.

The number of step portions of the stepped cup body 200 may be one as inthe example in FIG. 2A (step portion 270), or two or more as in theexample in FIG. 2B (step portions 450 and 470).

Further, a height position at which the step portion 270 (step portions450 and 470) is formed is not limited to the position illustrated inFIG. 2A or 2B and can be determined as appropriate.

In the disclosure, the stretch forming step is performed at least once,and may be repeated a plurality of times.

When the stretch forming step is performed a plurality of times, thenumber of repetitions of the stretch forming step varies depending onthe size of the container 100 desired, the body taper angle, and thethickness of the sheet metal from which the stepped cup body 200 isformed, and is preferably from 2 to 10 times, more preferably from 2 to5 times, still more preferably from 2 to 4 times, and particularlypreferably 3 times.

When the number of repetitions of the stretch forming step is excessive,an increase in the number of steps may increase the manufacturing loadand manufacturing costs, and a large influence of forming heat may causenon-negligible variations in finished dimensions, resulting in lowyields and low productivity. On the other hand, when the number ofrepetitions of the stretch forming step is not sufficient, manufacturinga container 100 having a large size or a large body taper angle requiresa large stretch ratio in one stretch forming step, which may causedamage such as breakage in the body portion 110.

In the stretch forming step, a manufacturing apparatus is used thatincludes a forming die including a diameter expanding punch 300 having atapered pressing portion 340 with a diameter larger than the innerdiameter of the small-diameter cylindrical portion 260 and an outerholding tool (not illustrated) having an inner face shape that matchesan outer peripheral face (tapered face 341) of the tapered pressingportion 340 of the diameter expanding punch 300 with a peripheral wall261 of the small-diameter cylindrical portion 260 interposedtherebetween.

The diameter expanding punch 300 has, for example, a cylindrical portion350 having a right circular cylindrical shape that is contiguous to anupper portion of the tapered pressing portion 340. The outer peripheralface of the tapered pressing portion 340 is the tapered face 341 withthe same taper angle over the entire circumference that serves as aworking face for diameter expansion. The taper angle of the tapered face341 is set to match the desired body taper angle of the tapered portion111 of the container 100, which is 5° in this embodiment. The taperedface 341 may be convex or concave so as to match the body taper angle ofthe tapered portion 111 of the container 100 desired.

The maximum outer diameter of the diameter expanding punch 300 issmaller than the inner diameter of the large-diameter cylindricalportion 280. Specifically, the diameter expanding punch 300 has an outercontour shape such that the diameter expanding punch 300 can be looselyinserted into the large-diameter cylindrical portion 280, that is, aslight gap exists between the inner face of the large-diametercylindrical portion 280 and the outer peripheral face of the cylindricalportion 350 of the diameter expanding punch 300.

The diameter expanding punch 300 can be reciprocated with apredetermined stroke length by a drive mechanism (not illustrated).

The apparatus for manufacturing a container according to the disclosureincludes a plurality of stretch forming dies with the diameter expandingpunches 300 having the tapered pressing portions 340 with differentouter diameters from each other. In the individual stretch forming stepsaccording to the method for manufacturing a container of the firstembodiment, the diameter expanding punches 300 having the taperedpressing portions 340 with different outer diameters from each other areused. When the maximum outer diameters of the tapered pressing portions340 of the diameter expanding punches 300 used for the first, second, .. . , nth stretch forming steps are d1, d2, . . . , dn, respectively,d1>d2> . . . >dn.

The taper angles of the tapered faces 341 of the tapered pressingportions 340 of the diameter expanding punches 300 used in theindividual stretch forming steps are substantially the same.

The minimum outer diameter of the tapered pressing portion 340 of thediameter expanding punch 300 used in the (n−1)th stretch forming step issmaller than the maximum outer diameter of the tapered pressing portion340 of the diameter expanding punch 300 used in the nth stretch formingstep following the (n−1)th stretch forming step.

The lengths of the tapered pressing portions 340 of the diameterexpanding punches 300 used in the individual stretch forming steps(axial lengths of the tapered pressing portions 340) are substantiallythe same, and a specific length is determined by the height of thetapered portion 111 in the body portion 110 of the container 100 desiredand the number of repetitions of the stretch forming step.

The taper angles and the axial lengths of the tapered faces 341 of thetapered pressing portions 340 in the individual diameter expandingpunches 300 are not limited to the same dimensions and need only be setto dimensions suitable for the specific cup shape of the container 100desired, respectively. For example, the tapered face 341 may be curved.The minimum outer diameters and the maximum outer diameters of thetapered pressing portions 340 of the individual diameter expandingpunches 300 also need only be set to dimensions suitable for thespecific cup shape of the container 100 desired, respectively.

In the stretch forming step according to the method for manufacturing acontainer of the first embodiment, as illustrated in FIG. 3A, thestepped cup body 200 is first placed on a base 370 with an open endportion 201 side facing the base 370 side, then the diameter expandingpunch 300 is coaxially placed in such a posture that the tapered face341 narrows toward the open end portion 201 of the stepped cup body 200(inverted truncated cone shape). Subsequently, as illustrated in FIG.3B, the diameter expanding punch 300 is relatively moved along thedirection of the cylindrical axis X from the side of the open endportion 201 of the stepped cup body 200 to a predetermined position(moved downward in FIG. 3B) with the outer holding tool (notillustrated) arranged outside the stepped cup body 200. When thediameter expanding punch 300 is moved, the tapered face 341 of thetapered pressing portion 340 begins to come into contact with a cornerportion 272 of the step portion 270, and the step portion 270 and partof the peripheral wall 261 are expanded in an inverted truncated coneshape, and the step portion 270 disappears. Then, when an upper end ofthe tapered pressing portion 340 of the diameter expanding punch 300 ismoved to a level position to be the upper end of the tapered portion111, the movement of the diameter expanding punch 300 is stopped, and asillustrated in FIG. 3C, a new bent portion 262 is formed in thesmall-diameter cylindrical portion 260 at a position corresponding to alower end of the moved tapered pressing portion 340, and a taperedcylindrical portion 251 having a tapered shape corresponding to thetapered face 341 of the tapered pressing portion 340 of the diameterexpanding punch 300 and the outer holding tool is formed. Further, apart of the stepped cup body 200 that was in contact with thecylindrical portion 350 of the diameter expanding punch 300 on the openend portion 201 side, or a part of the stepped cup body 200 that was notin contact with the diameter expanding punch 300, becomes the upper sideportion 113 of the container 100.

In the subsequent stretch forming step, by performing the similaroperation using a diameter expanding punch having a tapered pressingportion with a smaller diameter, a new tapered cylindrical portion isformed in a state in which the bent portion 262 formed in the precedingstretch forming step is expanded to overlap or to be adjacent to thetapered cylindrical portion 251 formed in the preceding stretch formingstep on the bottom portion 220 side so as to be smoothly connected toeach other in a tapered shape.

A lower part of the small-diameter cylindrical portion 260 of thestepped cup body 200 that remains unprocessed due to non-contact withthe diameter expanding punch 300 in the final stretch forming stepbecomes the lower side portion 114 of the container 100.

By repeating the above-described stretch forming step, a plurality oftapered cylindrical portions 251 are smoothly connected to form thetapered portion 111, thereby obtaining the container 100 with the bodyportion 110 having the tapered portion 111 formed with a uniform outwardexpanding angle.

The stretch ratio in the stretch forming step varies depending on thebody taper angle of the tapered portion 111 of the container 100 to bemanufactured, and is preferably from 2% to 15%, more preferably from 3%to 7%, and 5% in this embodiment at a height position corresponding tothe top part of the tapered portion 111. At a height positioncorresponding to just below the step portion 270 of the stepped cup body200 (the top part of the small-diameter cylindrical portion 260), thestretch ratio in the stretch forming step is, preferably from 1% to 10%,more preferably from 2% to 5%, and 3% in this embodiment.

The stretch ratio at the height position corresponding to the top partof the tapered portion 111 is defined by (A1−L1)×100(%) (Expression(1)), where L1 is a diameter at the height position to be the top partof the tapered portion 111 in the stepped cup body 200 prior to thefirst stretch forming step (can to be processed), and A1 is a diameterat the top part of tapered portion 111 of the container 100 after thelast (nth) stretch forming step (maximum diameter of the tapered portion111). The stretch ratio at the height position corresponding to justbelow the step portion 270 of the stepped cup body 200 is defined by(A2−L2)/L2×100(%) (Expression (2)), where L2 is a diameter at the toppart of the small-diameter cylindrical portion 260 in the stepped cupbody 200 prior to the first stretch forming step (can to be processed),and A2 is a diameter at the height position of the container 100, whichwas the top part of the small-diameter cylindrical portion 260, afterthe last (nth) stretch forming step.

It is preferable that the stretch ratio in the stretch forming step bein a range of 2% to 7% at any height position of the stepped cup body200.

The smaller the stretch ratio, the smaller the degree of plasticdeformation, and thus the tapered portion 111 having a desired taperedshape can be obtained without damage. When the stretch ratio isexcessive, there is a risk that the stress applied to the metal materialdue to processing will exceed the limit of plastic deformation and breakthe tapered portion 111 of the container 100.

As a sheet metal, similar to well-known two-piece beverage cans made ofan aluminum alloy, a sheet metal of an aluminum alloy having a thicknessof from 0.20 mm to 0.35 mm laminated with polyethylene terephthalate(PET) films having a thickness of approximately 0.01 mm on both sides isused.

By using such a sheet metal, after forming the container, the thicknessof the bottom portion in which the thickness of the material issubstantially maintained is from 0.20 mm to 0.35 mm, and the thicknessof the body portion 110 in the height range of 50±10%, when the totalheight of the container is 100%, has a thickness of from 0.10 to 0.22mm.

When the containers 100 according to the disclosure are stacked asillustrated in FIGS. 4 and 5 , at least one of the following areas (1)and (2) overlaps in contact: (1) a vicinity of an upper end of the outerface of the tapered portion 111 of the container 100 placed above and avicinity of an upper end of the inner face of the upper side portion 113of a container 100 u placed below, and (2) a vicinity of a lower end ofthe outer face of the lower side portion 114 of the container 100 placedabove and a vicinity of a lower end of the inner face of the taperedportion 111 of the container 100 u placed below, and the outer face ofthe tapered portion 111 of the container 100 placed above and the innerface of the tapered portion 111 of the container 100 u placed below donot come into close contact with each other by face.

On an upper end side of the container 100 above, a projecting portion112 projects from an upper end of the container 100 u below, and aprojecting height T of the projecting portion 112 is determined by aheight of the upper side portion 113, a height of the lower side portion114, a shape of the bottom portion 120, and the like.

In the example in FIG. 4 , the projecting height T is 8.0 mm, and theratio of the height T of the projecting portion to a height H of thecontainer 100 is 7.1%.

Note that the upper side portion 113 and the lower side portion 114 maybe formed so as to expand outward at angles different from the angle ofthe tapered portion 111, or only one of them may be provided, or neithermay be provided.

Further, the upper side portion 113 and the lower side portion 114 maybe tapered oppositely to the tapered portion 111 so as to narrow inward.

In a case in which the upper side portion 113 and the lower side portion114 do not exist, or are extremely small so that when stacked, the outerface of the bottom portion 120 of the container 100 placed above and theinner face of the bottom portion 120 of the container 100 u placed belowcan be in close contact, a bead, which is an independent contact portionthat projects to an inner face side of the body portion 110 and comesinto contact with an outer face of the container stacked above, may beprovided, thereby preventing the outer face of the body portion 110 ofthe container 100 placed above and the inner face of the body portion110 of the container 100 u placed below from coming into close contactwith each other.

The bead may be of any shape, direction, quantity, and location, mayproject to the inner face side, may project to the outer face side, or amixture of the inner and outer faces may exist.

Further, as long as a projecting portion functions as a contact portion,the projecting portion may be a point or a face projecting from thetapered portion 111 rather than the bead shape.

Further, the container 100 may be used as a can filled with a beverageor the like and subsequently provided with a lid member.

The lid member may be any stay-on-tab lid made of metal, a sheet made ofa layered body, a screw lid, or the like.

In a case in which the lid member is wound and tightened on the upperend of the body portion as a stay-on-tab lid, the upper end of the bodyportion of the container need only be subjected to trimming for thewinding and tightening and subsequently subjected to flanging that formsa face portion.

In a case in which the lid member is bonded by heat or other means tothe upper end of the body portion as a sheet composed of a layered body,the upper end of the body portion of the container may be imparted witha shape that includes a face portion to ensure the bonding area.Examples of the sheet composed of a layered body include aluminum foil,paper, a resin film, and a laminate material obtained by layering two ormore of these, and a thermal adhesive layer (heat-sealed layer) may befurther layered. As the thermal adhesive layer, a layer composed of anadhesive such as a known sealant film, a lacquer type adhesive, an easypeel adhesive, or a hot melt adhesive can be employed.

In a case in which the lid member is screw-fixed to the upper end of thebody portion as a screw lid, the projecting portion 112 of the upperside portion 113 or the like of the upper end of the body portion of thecontainer may include screw threads, or a lid member with a spoutincluding separate screw threads may be wound and tightened around theupper end of the body portion of the container to screw-fix the screwlid.

By matching the projecting portion 112 to the attachment form of the lidmember, it is possible to improve efficiency when storing andtransporting the container portion regardless of the type of lid member.

The method for manufacturing a container and the apparatus formanufacturing a container according to the first embodiment of thedisclosure have been described in detail above, but the disclosure isnot limited to the embodiment described above, and various changes canbe made within the scope of the disclosure described in the claims.

For example, in the method for manufacturing a container according tothe disclosure, not only the container in which the tapered portion ofthe body portion is formed into the shape that expands outward at thebody taper angle of from 2° to 15° at any location, but also followingcontainers can be manufactured: a container partially having a portionoutside the range of from 2° to 15° similar to the upper side portionand the lower side portion in the present embodiment, a curved containerin which the outward expanding angle of the body portion graduallychanges in a cross-sectional view, and a container having a plurality ofstepped portions on the body portion, and a container having a bodyportion with a combination of linear expanding, curved expanding,stepped portions, and the like.

For example, it is not limited to forming the body portion 110 bydividing the body portion 110 in the height direction in the individualstretch forming steps as in the first embodiment, but the body portion110 may be formed to gradually expand in the lateral direction in theindividual stretch forming steps by dividing the desired final bodytaper angle. A method for manufacturing a container according to asecond embodiment will be described below.

In individual stretch forming steps according to the method formanufacturing a container of the second embodiment, diameter expandingpunches are used that include tapered pressing portions having invertedtruncated cone shapes that have lengths (axial lengths of the taperedpressing portions) equivalent to a height of the tapered portion 111 ofthe body portion 110 of the container 100 desired, and that have taperedfaces with different taper angles from each other, and that havedifferent outer diameters from each other. When the taper angles of thediameter expanding punches used for the first, second, . . . , nthstretch forming steps are θ1, θ2, . . . , θn, respectively, θ1<θ2< . . .<θn is satisfied. When the maximum outer diameters of the taperedpressing portions of the diameter expanding punches used for the first,second, . . . , nth stretch forming steps are d1, d2, . . . , dn,respectively, d1<d2< . . . <dn is satisfied.

An angle difference between the taper angle θ(n−1) of the diameterexpanding punch used in the (n−1) stretch forming step and the taperangle θn of the diameter expanding punch used in the subsequent nthstretch forming step is, for example, approximately 2.5°. In the methodfor manufacturing a container according to the second embodiment, thetaper angle of the diameter expanding punch used in the first stretchforming step is 2.5°, and the taper angle of the diameter expandingpunch used in the second (last) stretch forming step is 5°.

In the stretch forming step according to the method for manufacturing acontainer of the second embodiment, as illustrated in FIG. 6A, first, astepped cup body 500 having one step portion 570 with an inclined stepface 571 is placed on a base (not illustrated) with an open end portion501 side facing the base 370 side, then the diameter expanding punch(not illustrated) is coaxially placed in such a posture that the taperedface narrows toward the open end portion 501 of the stepped cup body 500(inverted truncated cone shape). Then, the diameter expanding punch isrelatively moved along the direction of the cylindrical axis X from theopen end portion 501 side of the stepped cup body 500 (moved downward inFIG. 6A) with an outer holding tool (not illustrated) arranged outsidethe stepped cup body 500, and the movement of the diameter expandingpunch is stopped when the diameter expanding punch is moved to a levelposition in which the diameter of the entire face to be the taperedportion 111 is expanded by the tapered face of the diameter expandingpunch. When the diameter expanding punch is moved, as illustrated inFIG. 6B, the tapered face of the tapered pressing portion of thediameter expanding punch begins to come into contact with a cornerportion 573 on the inner side of the step portion 570, part of thecorner portion 573 on the inner side of the step portion 570 is expandedin diameter and disappears as the diameter expanding punch moves, a newstep portion 590 is formed by a remaining corner portion 593, and atapered cylindrical portion 551 is formed by being expanded in aninverted truncated cone shape that matches a taper angle (taper angleθ1) of the tapered face of the diameter expanding punch used.

In a subsequent stretch forming step, by performing the similaroperation using a diameter expanding punch having a tapered pressingportion with a large tapered angle (taper angle θ2), as illustrated inFIG. 6C, the corner portion 593 of the step portion 590, which is partof the corner portion remaining in the preceding stretch forming step,is expanded and disappears, and the tapered cylindrical portion 551formed in the preceding stretch forming step is further expanded indiameter to form a new tapered cylindrical portion 552 (the body portion110) having a larger taper angle (taper angle θ2) matching the taperangle of the tapered face of the diameter expanding punch used (taperangle θ2).

By repeating the above-described stretch forming step until the stepportion disappears, the body portion 110 is gradually expanded laterallyin diameter to form the tapered portion 111, thereby obtaining thecontainer 100 with the body portion 110 having the tapered portion 111having a tapered shape with a uniform outward expanding angle.

REFERENCE SIGNS LIST

While preferred embodiments of the disclosure have been described above,it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the disclosure. The scope of the disclosure, therefore, isto be determined solely by the following claims.

1. A method for manufacturing a container made of metal, including abottom portion and a body portion, being open on an upper face side, andhaving a shape in which the body portion expands outward toward theupper face side, the method comprising: (a) expanding a diameter of astepped cup body made of metal and having a small-diameter cylindricalportion having a bottomed cylindrical shape and a large-diametercylindrical portion with an opening on an upper face side and contiguousto an upper end of the small-diameter cylindrical portion via a stepportion by operating a diameter expanding punch having a taperedpressing portion that is smaller in diameter than an inner diameter ofthe large-diameter cylindrical portion and larger in diameter than aninner diameter of the small-diameter cylindrical portion of the steppedcup body along a cylindrical axis direction from an opening side of thelarge-diameter cylindrical portion, wherein step (a) is performed atleast once.
 2. The method for manufacturing a container according toclaim 1, wherein step (a) is repeated a plurality of times.
 3. Themethod for manufacturing a container according to claim 2, wherein step(a) is repeated from 2 to 10 times.
 4. The method for manufacturing acontainer according to claim 1 or 2, wherein an angle of the stepportion of the stepped cup body to a plane perpendicular to an axialdirection of the stepped cup body is from 0° to 60°.
 5. The method formanufacturing a container according to claim 1 or 2, wherein a diameterof a tapered pressing portion of a diameter expanding punch used in step(a) performed earlier and a diameter of a tapered pressing portion of adiameter expanding punch used in step (a) performed subsequently aredifferent from each other.
 6. The method for manufacturing a containeraccording to claim 1 or 2, wherein the body portion of the container isformed into a shape in which a line connecting an outer peripheral faceat 10% height and an outer peripheral face at 90% height from alowermost portion expands outward at an angle of from 2° to 15° when atotal height of the container is 100%, and when the two containers arestacked, a projecting portion of the container placed above projectingupward has a height of 20 mm or less from an upper end of the containerplaced below.
 7. The method for manufacturing a container according toclaim 6, wherein the bottom portion has a thickness of from 0.20 mm to0.35 mm, the body portion has a thickness of from 0.10 to 0.22 mm in aheight range of 50±10% when the total height of the container is 100%,and the body portion is formed into a shape in which the line connectingthe outer peripheral face at 10% height and the outer peripheral face at90% height from the lowermost portion expands outward at an angle offrom 3° to 10° when the total height of the container is 100%.
 8. Themethod for manufacturing a container according to claim 6, wherein aratio of the projecting portion to a height of the container is from 4%to 15%.
 9. The method for manufacturing a container according to claim6, wherein a ratio of the projecting portion to a height of thecontainer is from 5% to 9%.
 10. The method for manufacturing a containeraccording to claim 6, wherein the body portion includes a contactportion with a less area configured to avoid close contact with anothercontainer when the container is stacked with the other container.
 11. Anapparatus for manufacturing a container made of metal, including abottom portion and a body portion, being open on an upper face side, andhaving a shape in which the body portion expands outward toward theupper face side, the apparatus comprising: at least one stretch formingdie, each of the stretch forming die including a diameter expandingpunch having a tapered pressing portion that is configured to expand adiameter of a stepped cup body made of metal and having a small-diametercylindrical portion having a bottomed cylindrical shape and alarge-diameter cylindrical portion with an opening on an upper face sideand contiguous to an upper end of the small-diameter cylindrical portionvia a step portion by pressing along a cylindrical axis direction froman opening side of the large-diameter cylindrical portion and that issmaller in diameter than an inner diameter of the large-diametercylindrical portion and larger in diameter than an inner diameter of thesmall-diameter cylindrical portion of the stepped cup body.
 12. Theapparatus for manufacturing a container according to claim 11, whereinthe at least one forming die is a plurality of stretch forming dies. 13.The apparatus for manufacturing a container according to claim 12,wherein the number of the plurality of stretch forming dies is from 2 to10.
 14. The apparatus for manufacturing a container according to claim11 or 12, wherein an angle of the step portion of the stepped cup bodyto a plane perpendicular to an axial direction of the stepped cup bodyis from 0° to 60°.
 15. The apparatus for manufacturing a containeraccording to claim 11 or 12, wherein diameters of the tapered pressingportions of the diameter expanding punches included in the plurality ofstretch forming dies are different from each other.